1. Technical Field of the Invention
The present invention relates to mobile telecommunications systems and, in particular, to a method and apparatus for programming a mobile terminal with an address of a Home Location Register within a mobile telecommunications network.
2. Description of Related Art
Each mobile terminal and its associated subscription is uniquely identified by a network identification such as an International Mobile Subscriber Identity (IMSI) number. The mobile terminal IMSI is used by the serving mobile telecommunications network to identify the home Public Land Mobile Network (PLMN) and the Home Location Register (HLR) storing the subscription information associated with that particular mobile terminal. Such subscription information includes billing information, subscription category, subscriber feature data, and authentication data. This subscription information is needed by the serving mobile network to properly provide mobile service to the particular mobile terminal.
As an example, in the Global System for Mobile (GSM) system, a unique IMSI number is stored in each mobile terminal as well as in its associated HLR database. Accordingly, whenever a mobile terminal travels into a foreign Mobile Service Center (MSC) area and performs an initial registration, the MSC analyzes the IMSI number received from the mobile terminal and subsequently locates the home network and the HLR to obtain the necessary subscriber information.
Due to the competitiveness in the mobile telephone service industry and the flexibility demanded by mobile customers, some telephone service providers and operators are no longer willing to pre-encode within a mobile terminal the address representing a particular HLR. Pre-encoding an HLR network address as a part of an IMSI number before the mobile terminal is registered by a particular subscriber limits its sales area and thereby restricts its marketability. For example, if a mobile terminal is encoded with an HLR network address associated with a mobile network serving the Dallas, Texas area, service providers or operators are limited to selling that particular mobile terminal only within the Dallas area. Therefore, in order to remove the logical relationship between a particular mobile terminal and a particular HLR, service providers and operators have removed the HLR network address from the pre-encoded IMSI number.
However, removing the HLR network addresses from mobile terminal IMSIs creates functional problems within the mobile telecommunications network. If there is only one HLR within a particular PLMN, an IMSI number without the HLR network address is still capable of identifying the home PLMN and the only HLR associated with that PLMN. However, with the increase of mobile subscription numbers and services, it is likely that more than one HLR is needed to effectively service a particular PLMN area. As a result, without the HLR network address, whenever mobile service is requested from a mobile terminal, each HLR within that particular PLMN indicated by the transmitted IMSI number needs to check whether the requesting subscriber information from that particular mobile terminal is stored within its database. This implies employment of a trial-and-error search tactic to eventually locate the correct HLR. Another implementation might be to introduce a centralized database within each PLMN to store data correlating each IMSI with its associated HLR. Whenever a requesting message is received, the centralized database is first queried to locate the correct HLR. However, both methods are disadvantageous and inefficient requiring additional hardware components or processing time. Alternatively, the HLR network address is encoded into the Subscriber Identity Module (SIM) card or "smart card" (hereinafter referred to as a SIM card) associated within each mobile terminal after purchasing the mobile terminal and selecting a desired service provider. This requires detaching the SIM card from the mobile terminal and physically carrying it to the service provider, and is viewed as being inconvenient and cumbersome.
Accordingly, it would be advantageous to introduce a method and apparatus for remotely programming an address of a serving HLR in a mobile terminal.